Timbers Flashcards
Features of soft woods
- They grow in cooler climates
- Come from Coniferous trees
- They have a looser grain structure
- They are often used as a building material
- These are usually softer and easy to work with (due to having a looser grain)
- As the trees grow tall and straight, the manufacturer can cut it into long straight planks of wood.
- They grow quite faster and are cheaper
- They do not lose their needles.
Hardwoods
- Come from deciduous trees (lose their leaves in the winter)
- Tend to have a tighter grain so they are usually quite hard
- They can be very expensive
- They take 100 years to fully grow
Manufactured Boards features
- Made in many thicknesses
- Inexpensive so are often used instead of real woods
- Manufactured boards are often covered with a thin layer of real wood called a veneer to improve appearance or properties
- THESE ARE timber sheets which are produced by gluing wood layers or wood fibres together
- Made usually from waste wood
- They have been developed mainly for industrial production as they can be made in very large sheets of consistent quality.
Name the softwoords
Pine, Spruce, Douglas fir, Redwood, Cedar, Larch
Name the hardwoods
- Oak
- Ash
- Mahogany
- Teak
- Birch
- Beech
Man-made timbers
- Plywood
- Marine plywood
- Aeroply
- Flexible plywood
- Chipboard
- Medium density - fibreboard (MDF)
What are the stock forms of timber?
- Rough sawn
- Planed Sqaure Edge (PSE)
- Planed all round (PAR)
- Natural timber
- Manufacture board
- Mouldings
What does rough sawn mean?
The wood comes directly from seasoning and has rough surfaces produced from initial conversion. Rough sawn wood will have nominal sizes rather than accurate finished size.
What is PSE?
Planed square edge 9PSE0 wood has only one edge that is planed accurately; the rest are rough sawn. Planing removes about 3mm from the original normal size.
What is Planed all Round?
PAR wood has sides and edges that are all planed square, straight and level, leaving a smooth finish, and is ready to use. The PAR board is about 3mm smaller all round than the original rough sawn nominal size.
What are mouldings?
Some wood is made into mouldings such as skirting boards or wooden trims and are readily available in standard lengths up to approximately 4 metres.
What are veneers?
Thin slices of wood less than 3mm thick.
What happens when wood rots or burned?
Greenhouse gases are released, contributing to climate change.
Why are trees important?
They act as carbon ‘sinks’ that absorb the gases.
What does using a recycled timber product mean?
Using a recycled timber product reduces deforestation and retains the locked-in carbon.
What are the two types of seasoning on timbers?
- Natural seasoning
- Kiln seasoning
What is the method of natural seasoning?
It is an inexpensive method which involves stacking the wood under a shelter, protected from the rain. Air circulates between the planks to slowly remove the excess moisture. Air-seasoned wood is used for outdoor wooden products because it is seasoned to the same moisture content as its surroundings and therefore the wood will be less prone to defects.
What is kiln seasoning?
- Planks are stacked onto trolleys and placed in the kiln where both temperature and humidity are controlled. Initially, the kiln atmosphere is very steamy but this is gradually changed to become hotter and drier. Indoor products such as furniture will use kiln-seasoned wood because it has been seasoned to meet indoor conditions and will have a lower moisture content than air-dried wood.
Natural seasoning advantages
- Cheap
- Some say the timber is stronger than kiln seasoned
Natural seasoning disadvantages
- Every flow (a year per inch thickness
- Bugs and fungus survive
- Water content hard to control accurately
- Ends of planks can split
Kiln seasoning advantages
- Accurate water content achieved
- 12% or lower moisture
- Kills bugs and fungus
- Faster than natural seasoning
Disadvantages of kiln seasoning
- Expensive
What are some timber defects?
Splitting
Knots
Timber decay - Dry rot
Woodworm
What is splitting?
- Usually occurs at the end of a plank
- Ends are cut off to remove splits
- Generally an unavoidable problem
- Painting the ends of planks can help slow down the drying of the ends
What are knots?
Knots are where a branch was attached to the tree
- Live knots are ok and can be decorative
- However, dead knots must be avoided
What is timber decay - dry rot
- Serious problem caused by incorrect seasoning or poor building maintenance
- Dry rot is caused by timber being over 20% moisture content and not ventilated
Properties and uses of oak
Hardwood
Properties: Hard, tough, attractive grain, good weather resistance. Contains tannic acid which will corrode steel screws or fixings.
Uses: Furniture, flooring, boat building, cladding. Interior and exterior joinery.
Ash properties and uses
Hardwood
Properties: Tough attractive open grain pattern which makes it more flexible.
Uses: Tool handles, ladders, sport goods, laminating
Mahogany properties and uses
Hardwood
Properties: Can contain interlocking grain, making it more difficult to work. Rich dark red colour.
Uses: Indoor furniture, shop fittings and cabinets, veneers commonly used on manufactured boards.
Teak properties and uses
Hardwood
Properties: Hard, tough, straight grain, natural oils resist moisture, acids and alkalis.
Uses: Outdoor furniture, laboratory benches, traditional boat decks.
Birch properties and uses
Hardwood
Properties: Hard, straight close grained, resists warping
Uses: Furniture, indoor panelling, veneers used for birch-faced plywood construction
Beech properties and uses
Hardwood
Properties: Tough, closed grained, hard, available in steamed (white colour) and un-steamed (pink tinge), does not impart a taste of food.
Uses: Chairs, chopping boards, tools (mallets) steam bent laminated furniture, turned bowls
Pine properties and uses
Softwood:
Properties: Straight grain, knotty, can contain resinous knots.
Uses: Construction work, roof beams and timber frame construction, interior joinery.
Spruce properties and uses
Softwood
Properties: Straight grain, resistant to splitting
Uses: Indoor furniture
Douglas fir properties and uses
Softwood
Properties: Straight or slightly wavy grain, few knots, stable, good resistance to corrosion.
Uses: Veneers, plywood construction, joinery and construction work.
Larch properties and uses
Softwood
Properties: Hard, tough, attractive grain pattern fades to silver upon exposure outside, good resistance to moisture.
Uses: Garden furniture, cladding, decking, fencing
Cedar properties and uses
Softwood
Properties: Straight grain, can corrode ferrous metals due to acidic nature, low density, good sound damping, good resistance to moisture.
Uses: Exterior cladding, sheds, greenhouses, beehives, interior panelling
Plywood properties and uses
Manufactured boards
Properties: Thin layers of wood are placed and glued at 9 degrees to each other and compressed to form the board. Good strength in all directions, no grain weaknesses, always has an odd number of layers.
Uses: Structural work, desk tops, indoor furniture, floorboards
Marine plywood properties and uses
Manufactured boards
Properties: Similar construction to plywood but is gap and void-free and uses specialist water and boil proof (WBP) glue to provide resistance to moisture. Some higher quality marine plywood is also resistant to fungal attack.
Uses: Boat dashboards, boat lockers and panelling.
Aeroply properties and uses:
Manufactured boards
Properties: Plywood made from high-quality timber such as birch. Available in very thin sheets, lightweight, easy to bend around a support frame.
Uses: Gliders, laminated furniture, laser cut projects, jewellery items
Flexible plywood properties and uses
Manufactured boards
Properties: An odd number of layers glued together with the two outer layers made from open grained timber which allows the sheet to flex. Bent and glued around a former to achieve a solid shape.
Uses: Laminated furniture, curved panels
Chipboard properties and uses
Manufactured boards
Properties: Wood chips compressed with a resin such as Urea formaldehyde
Uses: Often veneered or covered with polymer laminate, kitchen worktops and units, shelving and flat-pack furniture
MDF properties and uses
Manufactured boards
Properties: It is compressed wood fibres, although sometimes urea formaldehyde is added as an additional resin. It has two smooth faces, available in either standard grade or veneered with a layer of timber.
Uses: Model making or mould making, furniture items such as bookcases, cabinets and desks.
Veneers properties and uses
Properties: Thin slices of wood less than 3mm thick.
Uses: Decorative coverings for manufactured boards
